1. Field of the Invention
The invention relates to an electromechanical brake, which is provided in particular as a vehicle brake for a motor vehicle.
2. Description of the Prior Art
Brakes of this kind are intrinsically known. In order to actuate them, i.e. in order to press a friction brake lining against a rotatable brake body to be braked, the brakes have an electromechanical actuating device equipped with an electric motor and a rotation/translation converting transmission via which the electric motor is able to press the friction brake lining against the brake body. Often, a reduction gear train is connected between the electric motor and the rotation/translation converting transmission. It is customary for the rotation/translation converting transmission to be a screw mechanism. Other mechanisms, for example a rack-and-pinion drive or a cam that the electric motor is able to pivot via the reduction gear train, thereby causing it to press the friction brake lining against the brake body can also be used to convert the rotating drive motion of the electric motor into a translating movement in order to press the friction brake lining against the brake body. It is also conceivable to use an electromagnet in lieu of the electric motor. In the case of a disc brake, the brake body is a brake disc. In the case of a drum brake, it is a brake drum.
One example of an electromechanical brake of this kind is disclosed in DE 102 55 192 A1. To modify the known brake into an auxiliary brake (parking brake), the known brake is equipped with a switchable freewheel, which in the engaged position, locks a motor shaft of the electric motor to prevent it from rotating in a releasing direction of the brake. The locking can occur directly on the motor shaft or indirectly, for example on a transmission shaft. In an actuation or application direction of the brake, the motor shaft is able to rotate freely even when the freewheel is engaged, thus allowing the brake to be actuated but not released. When the freewheel is disengaged, the motor shaft is able to rotate in both rotation directions. It is thus possible to apply and release the brake like a service brake. In the known brake, the freewheel is coaxially flange-mounted to a housing that accommodates the electric motor and the rotation/translation converting transmission.